1. Field of the Invention
This invention relates to a helical scan magnetic signal reproducing method and apparatus employing a magneto-resistive effect magnetic head.
2. Description of the Related Art
In a magnetic reproducing apparatus, such as a video tape recorder, audio tape recorder or a data storage system for a computer, employing a magnetic tape as a recording medium, there is adopted a helical scan system for improving the recording density to increase the recording capacity.
In this magnetic reproducing apparatus, a higher recording density and a larger recording capacity are desired. For realizing this higher recording density and a larger recording capacity, it has been proposed to use a magneto-resistive effect magnetic head (MR head) as a playback magnetic head in the helical scan magnetic recording/reproducing apparatus.
The MR head uses a magneto-resistive effect element (MR element) as a magnetically sensitive element for detecting the magnetic field from the recording medium, and is put to practical use as a playback magnetic head of the hard disc drive. In general, the MR head is higher in sensitivity than the inductive magnetic head and is able to develop a large playback output. Thus, by using the MR head as the playback magnetic head, it is possible to realize a still higher recording density and a still larger recording capacity.
Meanwhile, in a hard disc drive, the MR head is loaded on the floating slider, so that data is reproduced under a condition in which the MR head is floated over the magnetic disc. On the other hand, if the MR head is used for the helical scan system, data is reproduced from the magnetic disc as the MR head is kept in sliding contact with the magnetic tape.
However, if the MR head is kept in sliding contact with the magnetic tape, there is presented a problem that, even if the playback output of the MR head is high, the MR head is worn out due to its sliding contact with the magnetic tape. If the MR head is worn out, the playback output level is fluctuated to increase the noise and so-called dropout. For this reason, the helical scan magnetic reproducing apparatus employing the MR head as the playback magnetic head has as yet not been put to practical use.
It is therefore an object of the present invention to provide a magnetic signal reproducing method and apparatus of the helical scan system employing an MR head devoid of the above-described inconvenience.
In one aspect, the present invention provides a magnetic signal reproducing apparatus including a substantially cylindrically-shaped rotary drum, an inductive magnetic head loaded on the rotary drum so that at least a portion thereof is protruded from the outer periphery of the rotary drum, a magneto-resistive effect magnetic head loaded on the rotary drum so that at least a portion thereof is protruded from the outer periphery of the rotary drum, tape sort discriminating means for detecting the sort of the magnetic tape, and tape tension control means for controlling the tape tension of the magnetic tape. The amount of protrusion of the magneto-resistive effect magnetic head from the outer periphery of the rotary drum is selected to be smaller than the amount of protrusion of the inductive magnetic head from the outer periphery of the rotary drum. In reproducing information signals from the magnetic tape, the sort of the magnetic tape is detected by the tape sort discriminating means, and the magnetic head used for reproducing the information signals is selected from the group of the inductive magnetic head and the MR head depending on the results of detection. The tape tension in case of reproducing the information signals by the inductive magnetic head is controlled by the tape tension control means so as to be smaller than the tape tension when the information signals are reproduced by the magneto-resistive effect magnetic head.
In this magnetic signal reproducing apparatus, in which the amount of protrusion of the magneto-resistive effect magnetic head is smaller than that of the inductive magnetic head, the contact pressure between the magneto-resistive effect magnetic head and the magnetic tape is smaller than that between the inductive magnetic head and the magnetic tape. Also, if, in this magnetic signal reproducing apparatus, information signals are reproduced by the magneto-resistive effect magnetic head, the tape tension of the magnetic tape is increased by tape tension control means, thus assuring optimum abutment of the magneto-resistive effect magnetic head with the magnetic tape.
In another aspect, the present invention provides a magnetic signal reproducing method for reproducing magnetic signals using a magnetic signal reproducing apparatus including a substantially cylindrically-shaped rotary drum, an inductive magnetic head loaded on the rotary drum so that at least a portion thereof is protruded from the outer periphery of the rotary drum, a magneto-resistive effect magnetic head loaded on the rotary drum so that at least a portion thereof is protruded from the outer periphery of the rotary drum, tape sort discriminating means for detecting the sort of the magnetic tape, and tape tension control means for controlling the tape tension of the magnetic tape. The amount of protrusion of the magneto-resistive effect magnetic head from the outer periphery of the rotary drum is selected to be smaller than the amount of protrusion of the inductive magnetic head from the outer periphery of the rotary drum. In reproducing information signals from the magnetic tape, the sort of the magnetic tape is detected by the tape sort discriminating means, the magnetic head used for reproducing the information signals is selected from the group of the inductive magnetic head and the MR head depending on the results of detection. The tape tension in case of reproducing the information signals by the inductive magnetic head is controlled by the tape tension control means so as to be smaller than the tape tension when the information signals are reproduced by the magneto-resistive effect magnetic head.
In this magnetic signal reproducing method, employing an apparatus in which the amount of protrusion of the magneto-resistive effect magnetic head is selected to be smaller than that of the inductive magnetic head, the contact pressure between the magneto-resistive effect magnetic head and the magnetic tape is smaller than that between the inductive magnetic head and the magnetic tape. Also, if, in this magnetic signal reproducing apparatus, information signals are reproduced by the magneto-resistive effect magnetic head, the tape tension of the magnetic tape is increased by tape tension control means, thus assuring optimum abutment of the magneto-resistive effect magnetic head with the magnetic tape.